Brake control for coil winding machine



Aug. 14, 1956 s, HOFFMAN 2,758,795

BRAKE CONTROL FOR COIL WINDING MACHINE Filed April 10, 1953 2 Sheets-Sheet 1 55mm kw @K.

Aug. 14, 1956 s. A. HOFFMAN 2,758,795

BRAKE CONTROL FOR con WiNDING MACHINE Filed April 10, 1953 2 Sheets-Sheet 2 R llllll United States Patent BRAIG) CONTROL FORvCOIL 'VVINDING' MACHINE SvenA. Herman,- Penn'Twnshiiay Psi, as'signorto Allis- Chalmers Manufacturing Company, Milwaukee, Wis;

Application April-- 10,-;1953, Serial No. 647,884+

8 Claims. (Cli-242"4)' This ihvention relatesin eneral to machines for windirr'ga strand of material upon" a ring shaped core and p'articu'larlkjtdan' automatic means for varying. or centrolling the speed of rotation" .o'ftheshuttle of such" a machine" whereby the strand being unwound therefior'n onto" a" ring'sliapecl"core does not develop "any slack. The termstrantlis usedbro'ad'ly herein toin'clt lde" all such things as Wire, cord, .thr'ead, twine; ta'p'eo'r tithing.

Winning machines for applying strand to ring" shaped OTa'nnuIar'eIements' such" as cores oftransformers in which a rotary shuttlefis interrelated with thelbopcf the core; have been revided'with braking'means toesntrol the! tension of strand" as it" is unwound from the shuttle onto: the core; H-bweve'r; sucnbrakingmeans as pro= vided irrzthose nra'chinesh'ave' merely. been suggested in sueh'a mannerittiat they provide a constant frictionimedingalierotationof theshuttle and" are not automaticall' controlled.

In'accordance-withthis invention: the operatien of'silch machinescan be iniprovedby maki ng'suehbr'aking means auto-matte to tension the stfan'din" accordance with the tendency. of the: strand to develop slack'asitfis being unwound ifrom the shuttle onto thecoreinferrelatedwith the shuttle. That'is, during each revolutionof'the shitttle,-.,the-tension of the strand is automatically controlled by, varyin'gthe' action of the brakingmeans.

It is therefore an object'of this invention to' provideair improved'winding ,machine embodying a rotary shuttle ffom= which'strand material such as wire is-wonnd 'ontb a closed annular ring or core-interrelatd with"therotary shuttle...

Another object of ftlns invention is topro'videin a strand winding machine in which-thespeed-of 'the shuttle is variedwit'h each revolution of'the travelingrinfg of the winding. machine,. whereby. strand supplied' from" the shuttle to an'-interrelated member is maintainedunder tension...

O'bjectsandIadvantages other than those above set forth will. be apparent-from the fbllowihgdscription when read in connection withflth e acompanying drawings in which:

Fig. =1 xis a side elevation of the vwindingmachine having aorotary=shuttletonwindingzstrandjin this instance wife, thenefirom onto aring shapedcorethat to be interrelated with: the" shuttle, .made in accordance Y with i the teachings-lof-thisinvention; W

Fig -23s tatplan view of the*maehine-iliustrated in -F 1 with-=a--ring.,shap ed core and-core holding-z-means shown innposition om the windingmachine whereby. the wire maygbe wound about that core;

Riga-3 is-ean elevationsviewof the apparatus shown imiEignZ-ltaken zfromi the left hand side thereof showing wire beingi applied to the-core;-

Eig.t=4* is a :fr'onteleva-tionviewof the apparatus represented in Figa' 2;

Fig; 5 iis tamrenlarged sectional' view taken alongtline V -V ofi Fig.-:1; r

'ice

Fig. 6 is an enlarged' elevation" view partty in' seetion take'n'alofigline VI VI'dfFig; 1';

Fig. 7 is an enlarged elevation view of part 0t the rb tary shuttle" and traveling. ring taken -along"line"VII VI- I of Fig: lysho'wing'a segr'iiefitallock njie'ahsforthe'Cshiittl whereby it may be directly driven by the i traveling ring of the machine in order'to winda' supply of wire onto the shuttle; v

Fig. 8 is an enlargedelevationviewof'part'of the-rota'ry shuttle" and traveling ring of the viiiridi'n'g. machine with the segmental lock means attached thereto. This view' is takenfromthe right side of'the'se members as viewed'inFig'. 7;

Fig. 9is a diagrammati'c'view ofthero'taryshuttle and parf'of'the automatic braking means provided for'tensiohing the wire in aecordance with the teaching of this invention; with vari'oiis partsenlarged. This automatic braking means is shown as being in the release position; and" Fig. 10-is a diagrammatic view similar to Fige-9 illitlstra'tingjthe automatic brakingmeans in its position fully engaged with the rotary shuttle.

A strand'winding machine in whichthis invention is embodied comprises a rotary shuttle- 11 consti-tfitingua ring shapedelement'freely rotatable about its axis; This shuttle is supported between upstanding:sidetrames lil and'13' andhas a peripheral groove (see Fig; 5) into which a supply of wirestra-nd type material is Wound. This shuttle is rota-ted ab out it s aXisbyfa travelingtgear ring 14'juxtapositi0ned the-shuttle tobe supported betweenthe side/frames 12"and I S WltHthBiI axes coincident A s/a matter of conve'nience the'axes are-illustrated as on a h orizontal line. V v

Fig.5 illustrates the side by' side positioning-of the traveling..rings .and shuttle. That cross sectional'view is taken through a wire guide means (referred to below) attached to the travelingring and'illustrates how the shuttle and ringaa-re supported between the; verticallyv disposedside'frames; Boththe shuttle and 'theringrzhave laterally, extending. rims 16 and 11, respectively; that are continuous for the full circillar'length ofthe respective member of which they are a part. The inside-faees-of the-sidefrarnes have: continuouscircular-grooves 18 and 19 into which 1 the laterallyextending. rims of; the ad-j'aj cent shuttle or traveling ringare-disposed'with clearance fit. These side-frames are clamp edtogether by: bolts-2'1 and have space rs 22 disposed between them toallowfor the shuttle and traveling ringrto be confined between thei-r inside faees with some clearance between-the shuttl'e the traveling ring and theside iframes.

Suitable-meansis-carried-by the traveling :ring'toguide Wire as-itunwinds from the shuttle. Preferabljt a pulley 26 and a wire-guide 27' are-carried onthe traveling": ring, the milley beingsrotatably. attaehedthere'to by.-pin-28,-:and the wire guide being suitably fixed to the traveling-wing as- -by-boit 29i As cambe -best-seeh from-Figs;- 5 and 6';=-the w-ire-guide and'thepulley areon "that's'ideof thetravelingv ring. which is immediatelyiadjaeent the-inner hat sideof the shuttle". And the-lip-of the guide overhangs the side portion ofthe shuttle. In ord'erto =aceommodate-the phlley anti the Wire guide 'so that theyrjmay. be'carriedby the-traveling ringsimmediately. adjaeent the shuttle;- a portion o'f'the inner-side-of-the traveling ring is removedfi Thus, Wire drawmfrom-the shuttle is 'guidedover the-pulley and be. tweenthe traveling ri-ngrand theshuttle onto-the core interlin-king the shuttle-and -traveling ring;-

Any. suitable -=.d-riving: means may be'provided for the traveling ringe- In-the illustrated embodiment; gearteth are -cut-in the peripheral edge 'portionT-o*-the 5 traveling ring. These=teethmesh with a pair-ot --idlez /gears? 31; :32

that are rotated by drive gear 33 of a variable speed drive gear train 34 turned by motor 35. The idler gears are spaced apart a distance predetermined in accordance with a gap in the traveling ring so that one or the other of those idler gears is always engaged with the traveling ring.

In the side frames 12 and 13 there are coincident openings 23 large enough for receiving a ring shaped core 24 onto which the wire carried by the shuttle is wound. A fixed rest is provided for that core and comprises a table surface 25 disposed horizontally and fixed by suitable means (not shown) to the frames.

In addition, as shown in Figs. 2 to 4, suitable, adjustable holding means is attached to the table surface for holding the core. Preferably, this means comprises three similar work holding clamps disposed on the table 120 from each other. Each of these clamps is attached to the table surface at its base by a hand screw 42. Each has an upstanding support 43 with a vertical slot 44 therein from which lateral member 46 extends. This lateral member is movable to be positioned at different levels spaced above the table and carries a roller which is in contact with the upper surface of the core when the machine is ready for operation. The roller is provided with a rubber like surface so as not to cause damage to the wire wound onto the core. Any suitable means, such as hand tool 47, may be provided for rotating the core about its axis as turns of the wire are wound thereon.

In order to interlink or interrelate the core with the shuttle, there is a removable shuttle segment 51 having length about equal to the height of the openings 23 in the side frames. A similar removable segment is not required for the traveling ring which instead may have a gap 52 in its loop corresponding to the approximate height of the openings in the side frames. As mentioned above, however, the length of this gap must be less than the distance between the two idler gears 31 and 32 so that the traveling ring may be constantly driven.

Since the shuttle is normally freely rotatable, a look.- ing means is provided for interconnecting the shuttle with the traveling ring whereby the shuttle may be driven by the traveling ring in a reverse direction to wind a length of wire into the peripheral groove of the shuttle. This locking means preferably is adapted to the removable shuttle segment (Figs. 7 and 8) and constitutes member 53 having an abutment which is disposed to extend laterally of the inner side of the shuttle into the gap of the traveling ring, thereby abutting one end edge of the traveling ring. Screw 54 is carried by the abutment member and is turned into a threaded hole in the side of the shuttle, clamping the abutment member to the shuttle. If desired the abutment member may include a finger like extension 56 which fits into a slot provided in the traveling ring. Of course, where this extension is utilized the length of the abutment member must be less than the length of the gap in the traveling ring so that the shuttle lock means may be easily installed and removed.

In the operation, the shuttle is rotated about its axis as the result of the traveling ring being driven by idler gears 31 and 32. As the pulley and guide of the traveling ring move in their circular path interlinking the core, wire is applied to the core by being drawn from the shuttle. This causes the shuttle to be pulled and to rotate about its axis. The position of the pulley relative to the core is constantly changing during each revolution. Certain of the relative positions of these two elements are illustrated diagrammatically in Figs. 9 and 10. Fig. 9 shows that for approximately one-half of the revolution, the length of wire drawn from the shuttle and extending between the core and the pulley is increasing. Whereas, as shown in Fig. 10, during the approximate other half revolution, the length of wire is decreasing. But since the shuttle is freely rotating, being motivated by wire being pulled therefrom, and since the aforesaid length of wire drawn from the shuttle is diminishing during approximately the second half revolution of the traveling ring, a problem of slack in the wire develops. The momentum of the rotating shuttle combined with the diminishing required length of wire results in an undesired slack and looping of the wire. In accordance with the teaching of this invention this problem is avoided by automatic means embodied in the winding machine for keeping wire drawn from the shuttle under tension at all times.

Figs. 3, 4, 9 and 10 illustrate a preferred embodiment of this automatic means by which a restraining force is automatically applied to the shuttle during the approximate half revolution of the traveling ring that slack normally would occur in the length of wire between the shuttle and the core.

This means includes a brake shoe 61 which engages a continuous surface of the shuttle and automatic brake shoe actuating means for synchronizing the operation of the brake shoe with rotation of the traveling ring and therefore substantially with the shuttle rotation.

The brake shoe is disposed between the side frames 12 and 13 adjacent the inner peripheral surface of the shuttle. Arm 63 is attached to the brake shoe and projects laterally through side frame 13; rod 64 is attached to arm 63 outside the frame. Two vertically aligned spaced guides 66 and 67 are attached to side frame 13 by suitable means such as welding. Rod 64 extends downwardly through those two guides. The lower portion of this rod is threaded and carries nut 68 which is positioned intermediate the two guides. Spring 69 encircles the rod with its upper end abutting the upper guide and its lower end abutting the nut. The position of this nut on the rod may be adjusted as a means to vary the spring compression. Rod 64 is keyed to cooperate with keyway 71 cut in the lower guide, thereby keeping the rod and the attached brake shoe properly aligned with respect to the shuttle surface against which the brake shoe is applied by the spring, biasing rod 64 to force the brake shoe into engagement with the shuttle surface.

During each revolution of the traveling ring the frictional force exerted by that brake shoe on the shuttle is adjusted in accordance with the tendency of the wire to develop slack. For example, as shown in Fig. 9 when the length of wire between the shuttle and the core should be increasing, the brake shoe may be completely released from engagement with the shuttle, and when the length of wire between the shuttle and the core should be decreasing as shown in Fig. 10, the brake shoe is applied to the shuttle.

The pulley is gear driven at a constant speed; whereas, the speed of the shuttle is varied by action of pulling wire therefrom and by the brake means. It is not necessary to stop or reverse rotation of the shuttle in order to obtain the desired decrease of that length of wire during the second approximately half revolution. Instead, that length of wire is decreased by slowing the shuttle speed without slowing the pulley speed. Since the pulley is gear driven at substantially constant speed, the reduction of speed of the shuttle by the automatic braking action effectively results in the shuttle taking up part of that length of wire. That is, the shuttle, though continuing to move in the direction the pulley is moved, is slowed down and thereby made to have motion in the opposite direction relative to the pulley so that the desired length of the wire is taken up by the shuttle. Then, by automatically releasing the brake during the next half revolution, the shuttle may be pulled at an increasing speed to release the required additional length of wire.

To synchronize the release and application of the brake shoe with the revolution of the traveling ring, rod 64 is reciprocated in response to the rotation of the traveling ring. Means for reciprocating that. rod each revoimmense lution of the traveling ring preferably compriseaazmember (oscillated at alfrequency corresponding to the speedrof revolution of the traveling ring. This oscillatingimeniber iis :lever 72, which pivots .at 73 on aiipin-fixed 'to ,the -frame-of the machine. efiected by cam 74 attached -to shaft 75 of ,gear 76 driven byspinion 77 carried on the :shaft of drivezgear '33, ascan be:seen:in.Fig. cl. The size oflthese gearsiis such that'the cam rotates onerevolutionfor each revolu- -tion of the travelingrringv vIn theillustrated-embodiment=thescam is designed so that during the 'half revolution :represented in Fig. 9, llever 72=is, pivoted to acteagainstthe'rspring overcoming :thespring action. That is, thellever releases the :brake .shoe. Andrduringxthe approximatezhalf revolutionsrepresented in Fig. 10, the lever is pivoted-so as not to interfere with the spring, 'whereby the spring is effective toapplymhe .brake shoeto the'ishuttle. Fig. 3 is a "variation of Fig.il0,in whichthe bolt in lever 72 has been extended so it vcontinues to contact rod 64 when the lever releases :the brake, rather than move entirely out ;of-:engagement=with rod :64 assin1Fig. 10.

The brake shoe may be completelytreleasedsand locked inthe released 'position when desiredyas'when-a'suPPly of wire is ':being wound .into the peripheral groove of.

1 the shuttle preparatory to unwinding 1 the wire therefrom .onto a core. This release means is manual (seen in Figs. '3 and 4) .c0mprisingan .arm' 78 pivotally connected :to post 79 of the-frame of the machine. .This manually oper- .-able.arm'carries an adjusting screw-81 medially thereon.

Theadjusting screw normally does not interfere with-the oscillationof the lever'by the cam. Arm 7 8zextends throughplate 82 which is:lsotted.soithat'thearm may be'moved downwardly and. laterally to.'a position wherein the arm is"held.by:..the.plateand wherebyfthe armpivotslever 72 and-vmoves the'brakeshoetiaway fromthe-sur- 1'. face: of the shuttle. Spring-83zis attached: totheanneand to". the frame of the machine: above .the arm toun'ormally hold'the arm-againstithe upper :endvof the slotin plate "82 in which position the arm doesnotinterfere with'.

the automatic action of the: cam. Of: course, the spring ialsoholdsithe arm-in the offset release-position as the spring tensions the arm binding zit against .the foffset portion of the slot in the plate.

Figs. -2, 3' and 4 -also show armeanszfiormounting the number of turns .of:the.-wire that'are'wound on a core. This counting device 84 is chain driven by sprocket 85 attached to .cam shaft 75.

.Although but a single embodiment of the ;'present invention has .been illustrated and described, it will be apparent to one skilled in th'e'art that various changes 4 and modifications maybe ma'de'therein without departing fromthe spirit'of the'invent'ron 'orfrom the" scope of the appended claims.

:It isclaimed and desired to. secure by Letters Patent:

1. A machine for winding strand on a ring element, comprising a traveling ring to be interlinked with said element, means for rotating said traveling ring about its axis, a ring shaped shuttle having a peripheral groove for containing a supply of strand to be wound on said element and having a continuous braking surface, a fixed frame for supporting said traveling ring and said shuttle juxtapositioned with their axes coincident, strand guiding means carried by said traveling ring through which strand drawn from said shuttle is passed in winding about said element whereby said shuttle is rotated about its axis as said strand is unwound therefrom, and intermittently operable braking means for controlling the speed of said shuttle to tension the strand as it is unwound from said shuttle, said braking means comprising a movable brake shoe disposed adjacent said surface of said shuttle, means for moving said shoe into engagement with said surface of said shuttle, means to periodically act against said moving means to move said shoe out of engagement with said surface of the shuttle to The oscillation of-that lever is aviary :the engagementzofnsaidashee \with said; surface-10f -said:shuttle, and; means .ssynchronizing the ;movement :of saidperiodic means with the :rotation :of said traveling ring.

2. -'Aamachineifor-windingstrand on a.core comprising :aztraveling ringctorbe interlinked with said core,.-a.=ring shaped shuttlez having a peripheral groove :for containing azsuppl-y of strand to bewoundon sa-idcorewand having :-a continuous pbrakingsurface, a frame vfor supporting said traveling ring and said corejuxtapositioned with (their axes coincident, means for rotating said traveling-ring raboutitsax-is, strand guidingimeansscarried by saidrtrav- :eling 1 ring through which strand r drawn from vsaid shuttle "iszpassedsinwinding about said core whereby said shuttle 'ist rotated! about its axis, and-intermittently operable'braking means for controlling the speed of-said shuttle to tension the strand as it is being -unwound from :said

, shuttle, .said braking means 1 comprising :a ;movable fricition-member'tdisposedwadjacentsaid surface of saidtshuttle, :biasing means for moving saidfn'ction'member into =en- -gagement .with said surface,- -cam means rotated in synchronism with the l rotation :of said traveling ring to act against: said biasing-means to vary the; frictional engage- -ment of :said friction s-member with said surface, and means:sy-nchronizing the movement of-said cam with the notation-of said :traveling ring.

-3. 'Aamachine for winding strand-about a core com- :prising a=a :traveiing zring, =a'aring shaped shuttle having 'meansrfor carrying; a supply .of strand for :winding on said core, *a frame for supporting :said traveling ringand vsai'dz-shuttle juxtapositioned with their :axes substantially acotincident,rmeans-rcarried bysaid traveling ring to pull sstrandirom said shuttle thereby rotating said -.shuttle, i intermittently: operable braking: means; for controlling .the rspee'drrof :rotationxofzsaidashuttleduring its rotation .to prevent slack aof the strand being unwound from said ushuttie-znntonsaid .core,:said braking means comprising ..:a movable :brake shoe disposed to engage with said .:sh11tt-.l'e, actuatingmeans attached to'said shoe, meanst conacting :with said frameiandsaid::actuating means to bias -sards"shoe to ,=saidwshutt-le -to cause the friction-between esaid shoe and: said shuttle, means to: move said-.actuating means rto varyzthe Efrictionalwengagement of said zshoe -witlrsaid3shnttle, anfdt means-synchronizing the movement of said moving means with the rotation of said traveling 4. sAsmachine: for winding: strand 1 about a 1 com comiprisingr a traveling rring, 1a ring :shaped shuttle :havi'ng sacperipheral groove for containing a: supply of strand for windingeon sa-idcore, a frame-for supporting said travelzingmingnandashuttle' juxtapositioned :with' their axes subistantiai'lyzcoineidentymeans;carriedcby said' traveling ring -to-'- pull *rstran'd fromxsaid :shuttle thereby rotating :said :ashuttle, intermittently-r operable braking. means for controlling the:- speed ?of :rotation tofsaid ;shuttle :to .prevent ss'lack'rofcthe' strandrbeingnnwound' from: said: shuttle onto said core, said braking means disposed to engage said shuttle and comprising a movable brake shoe, an actuating rod attached to said shoe, rod guide means attached to said frame, biasing means disposed to act between said frame and said rod to move said shoe with respect to said shuttle to cause friction between said shoe and said shuttle, means to move said rod to vary the frictional engagement of said shoe with said shuttle, and means synchronizing the movement of the rod moving means with the rotation of said traveling ring.

5. A machine for winding strand about a core comprising a traveling ring, a ring shaped shuttle having a peripheral groove for containing a supply of strand for winding on said core, a frame for supporting said traveling ring and shuttle juxtapositioned with their axes substantially coincident, means carried by said traveling ring to pull strand from said shuttle thereby rotating said shuttle, intermittently operable braking means for controlling the speed of rotation of said shuttle to prevent slack of the strand being unwound from said shuttle onto said core, said braking means disposed to engage said shuttle and comprising a movable brake shoe, an actuating rod attached to said shoe, rod guide means attached to said frame, biasing means disposed to act between said frame and said rod to move said shoe with respect to said shuttle to cause friction between said shoe and said shuttle, cam means and a lever, said lever pivotably attached to said frame having one end in contact with said rod whereby movement of said lever results in movement of said rod and having its other end engaged with said cam means, said cam means oscillating said lever about its pivot point to vary the engagement of said shoe with said shuttle, and means synchronizing the movement of the cam means with the rotation of the traveling means.

6. A machine for winding strand on a ring structure, comprising a traveling ring element to be interlinked with said structure, means for rotating said traveling ring element about its axis, a ring shaped shuttle element having a peripheral groove for containing a supply of strand to be wound on said structure and having a continuous braking surface, a frame element supporting said traveling ring element and said shuttle element juxtapositioned with their axes coincident by means comprising a continuous circular projection carried by certain of said elements disposed within and coacting with a continuous circular groove contained by the other of said elements, strand guiding means carried by said traveling ring element through which strand drawn from said shuttle element is passed in winding about said structure whereby said shuttle element is rotated about its axis as said strand is unwound therefrom, and intermittently operable braking means for controlling the speed of said shuttle element to tension the strand as it is unwound from said shuttle element, said braking means comprising a movable brake shoe disposed adjacent said surface of said shuttle element, means for moving said shoe into engagement with said surface of said shuttle element, means to periodically act against said moving means to move said shoe out of engagement with said surface of said shuttle to vary the engagement of said shoe with said shuttle, and means synchronizing the movement of said periodic means with the rotation of said traveling ring.

7. A machine for winding strand on a ring element, comprising a traveling ring to be interlinked with said element, means for rotating said traveling ring about its axis, a ring shaped shuttle having a peripheral groove for containing a supply of strand to be wound on said element and having a continuous braking surface, a frame, the inside faces of said frame having continuous circular grooves, said traveling ring and said shuttle having laterally extending rims, said laterally extending rims disposed within said continuous circular grooves supporting said traveling ring and said shuttle juxtapositioned with their axes coincident, strand guiding means carried by said traveling ring through which strand drawn from said shuttle is passed in winding about said element whereby said shuttle is rotated about its axis as said strand is unwound therefrom, and intermittently operable braking means for controlling the speed of said shuttle to tension the strand as it is unwound from said shuttle, said braking means comprising a movable brake shoe disposed adjacent said surface of said shuttle, means for moving said shoe into engagement with said surface of said shuttle, means to periodically act against said moving means to move said shoe out of engagement with said surface of said shuttle to vary the engagement of said shoe with said shuttle, and means synchronizing the movement of said periodic means with the rotation of said traveling ring.

8. A machine for winding strand on a ring element, comprising a traveling ring to be interlinked with said element, means for rotating said traveling ring about its axis, a ring shaped shuttle having a peripheral groove for containing a supply of strand to be wound on said element and having a continuous braking surface, a frame for supporting said traveling ring and said shuttle juxtapositioned with their axes coincident, strand guiding means carried by said traveling ring through which strand drawn from said shuttle is passed in winding about said element whereby said shuttle is rotated about its axis as said strand is unwound therefrom, locking means for interconnecting said shuttle with said traveling ring whereby said shuttle is driven by said traveling ring in a reverse direction for winding a length of wire onto said shuttle, and intermittently operable braking means for controlling the speed of said shuttle to tension the strand as it is unwound from said shuttle, said braking means comprising a movable brake shoe disposed adjacent said surface of said shuttle, means for moving said shoe into engagement with said surface of said shuttle, means to periodically act against said moving means to move said shoe out of engagement with said surface of the shuttle to vary the engagement of said shoe with said shuttle, and means supported by said frame to hold the periodic means against the moving means to retain the shoe out of engagement with said shuttle as the shuttle is rewound.

References Cited in the file of this patent UNITED STATES PATENTS 1,420,744 Pierce June 27, 1922 1,635,288 Pierce July 12, 1927 1,862,206 Tauchmann June 7, 1932 2,123,254 Pash July 12, 1938 2,444,126 Wirth June 29, 1948 2,606,723 Burdulis Aug. 12, 1952 FOREIGN PATENTS 573,639 Great Britain Nov. 29, 1945 

